Wireless communication systems employ power amplifiers for increasing the power of radio frequency (RF) signals. In a cellular base station, for example, a Doherty power amplifier may form a portion of the last amplification stage in a transmission chain before provision of the amplified signal to an antenna for radiation over the air interface. High gain, high linearity, stability, and a high level of power-added efficiency are characteristics of a desirable power amplifier in such a wireless communication system.
In the field of power amplifier device design, it is becoming increasingly desirable to achieve concurrent multi-band, broadband amplification. To successfully design a wideband power amplifier device for concurrent multi-band, broadband operation in a Doherty power amplifier circuit, for example, it is desirable to enable a good broadband fundamental match (e.g., over 20 percent fractional bandwidth) to appropriately handle harmonic frequency interactions, and to enable a wide video bandwidth. However, achieving these goals continues to provide challenges to power amplifier device designers.